Efficient CuInS ₂ /ZnS Quantum Dots Light-Emitting Diodes in Deep Red Region Using PEIE Modified ZnO Electron Transport Layer

In this study, the enhanced device performance of CuInS ₂ /ZnS quantum dots-based light-emitting didoes (QLEDs) for photomedical applications using polyethylenimine ethoxylated (PEIE)-modified ZnO as electron transport layer has been reported. The device enhancement is investigated by applying time-resolved photoluminescence and transient electroluminescence spectra. The results show that the modification of PEIE on ZnO layer limits the electron injection into quantum dots layer and reduces the accumulation of electrons at ZnO/QD interface. This provides an effective way to suppress the charging processes of quantum dots and thus enhance the device efficiency. As a result, the synergistic effect of PEIE modifying layer leads to a record current efficiency of 2.75 cd A ⁻¹ for the CuInS ₂ /ZnS-based QLEDs with deep red emission at 650 nm.